Many causes exist that led to the rise of dictatorships after WWI. After the war, Russia, Italy, and Germany found themselves in situations that allowed dictators to rise to power. The countries were all in extreme situations, both economically and politically, that became a fertile ground for future dictators to seize control. As well, people naturally desire order, and after WWI, much of Europe was still in chaos. The dictators promised social order even though they destroyed many peoples' lives and took away personal freedom.
In Russia, Stalin used the political upheaval after the Russian Civil War to win favor under Lenin and then become absolute dictator with a totalitarian form of government. His father was a shoemaker who died a vagrant, yet Stalin's ambition spurred him on in politics. Stalin convinced the people that the State had total control over them, and he ruled by terror from 1929-1953.
In Italy, Mussolini, called, Il Duce (The Leader), rose to power creating a Fascist regime. He was the son of a humble blacksmith, and he rose to power by organizing unemployed war veterans, called Black Shirts, to terrorize his political opponents. He controlled the media and convinced the people he was truly a perfect leader from 1922-1943.
Lastly, Hitler rose to power after Germany faced many sanctions after WWI, including Article 231, the "War Guilt Clause" in the Treaty of Versailles, forcing Germany to pay reparations for the war. His father had been a state worker, yet Hitler's ambition was limitless. He found the period of unrest in Germany to be a perfect time to rise to power, using propaganda to establish the Nazi Party and an absolute dictatorship from 1933-1945.
Three leaders rose to absolute power creating dictatorships that would definitely influence history using political, economic, and social unrest as their stepping stones.